CBSE Class 11 Biology Chapter 3: Plant Kingdom NCERT Solutions
This resource provides comprehensive NCERT Solutions for CBSE Class 11 Biology, Chapter 3: Plant Kingdom. It covers key concepts such as the classification of algae into Chlorophyceae, Phaeophyceae, and Rhodophyceae, detailing their distinguishing features like photosynthetic pigments, stored food, cell wall composition, and flagella. The solutions also explain the crucial process of reduction division (meiosis) and its occurrence in the life cycles of various plant groups, including liverworts, mosses, ferns, gymnosperms, and angiosperms. Understanding these topics is vital for grasping plant diversity and reproduction. These solutions are designed to help students clarify doubts, reinforce their learning, and prepare effectively for their board examinations by offering clear, step-by-step explanations.
Quick info
| Board | CBSE |
|---|---|
| Class | Class 11 |
| Subject | Biology |
| Session | 2026 |
| Language | English |
| Type | NCERT Solutions |
| Chapter | Chapter 3: Plant Kingdom |
Chapter summary
Chapter 3 of the NCERT Class 11 Biology textbook focuses on the Plant Kingdom. These solutions provide detailed answers to the exercises, covering the classification of algae based on pigments, stored food, and cell structure. It also elaborates on the timing and location of reduction division in the life cycles of diverse plant groups like bryophytes, pteridophytes, gymnosperms, and angiosperms, aiding students in understanding plant reproduction and evolution.
Learning outcomes
- Understand the basis of algae classification into Chlorophyceae, Phaeophyceae, and Rhodophyceae.
- Identify the major photosynthetic pigments, stored food, cell wall composition, and flagellar characteristics of different algal classes.
- Explain the process and significance of reduction division in the plant life cycle.
- Determine when and where reduction division occurs in liverworts, mosses, ferns, gymnosperms, and angiosperms.
- Differentiate between the life cycles of major plant groups concerning sporophyte and gametophyte stages.
Topics covered
Paper topics
- Algae Classification
- Chlorophyceae
- Phaeophyceae
- Rhodophyceae
- Photosynthetic Pigments
- Stored Food in Algae
- Cell Wall Composition of Algae
- Flagella in Algae
- Reduction Division (Meiosis)
- Life Cycle of Liverworts
- Life Cycle of Mosses
- Life Cycle of Ferns
- Life Cycle of Gymnosperms
- Life Cycle of Angiosperms
Important topics
- Basis of Algae Classification
- Distinguishing Features of Chlorophyceae, Phaeophyceae, Rhodophyceae
- Occurrence of Reduction Division in Plant Groups
- Sporophyte vs. Gametophyte Stages
- Reproductive Structures and Meiosis
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Questions and Solutions
Question 1
Algae are classified into three principal classes: Chlorophyceae (green algae), Phaeophyceae (brown algae), and Rhodophyceae (red algae). The primary criteria used for this classification are:
- Major photosynthetic pigments: The types and abundance of chlorophylls and accessory pigments like carotenoids and phycobilins vary among these classes.
- Form of stored food: The primary carbohydrate reserve synthesized and stored within the algal cells differs significantly.
- Cell wall composition: The materials that constitute the cell wall, such as cellulose, algin, pectin, and polysulphate esters, are distinct for each class.
- Number and position of flagella: The presence, number, and location of flagella in the motile reproductive cells (if present) are important distinguishing features.
For instance, Chlorophyceae possess chlorophylls a and b, store food as starch, have cellulose cell walls, and typically have two equal, apical flagella. Phaeophyceae contain chlorophylls a and c along with fucoxanthin, store food as mannitol and laminarin, have cell walls of cellulose and algin, and usually possess two unequal, lateral flagella. Rhodophyceae contain chlorophylls a and d along with phycoerythrin, store food as floridean starch, have cell walls of cellulose, pectin, and polysulphate esters, and lack flagella entirely.
Question 2
Reduction division, also known as meiosis, is a fundamental process in sexual reproduction that reduces the chromosome number by half. Its occurrence and location vary across different plant groups:
Liverwort: In liverworts, the dominant plant body is the haploid gametophyte. Reduction division occurs within the capsule of the sporophyte (which develops on the gametophyte) to produce haploid spores.
Moss: Similar to liverworts, the gametophyte is the dominant phase in mosses. Reduction division takes place in the capsule of the sporophyte, which grows from the gametophyte, to form haploid spores.
Fern: Ferns exhibit a dominant diploid sporophyte generation. Reduction division occurs within the sporangia, typically found on the underside of specialized leaves called sporophylls, to produce haploid spores.
Gymnosperm: In gymnosperms, the sporophyte is the dominant generation. Reduction division occurs within the microsporangia (located in pollen sacs of microsporophylls) to produce microspores (pollen grains), and within the megasporangia (located ovules on megasporophylls) to produce megaspores.
Angiosperm: In angiosperms, the sporophyte is the dominant generation. Reduction division occurs within the anthers of the stamen to produce microspores (pollen grains), and within the ovule (specifically in the megasporangium inside the ovary) to produce megaspores, which develop into the female gametophyte.
Common mistakes
- Confusing the specific pigments or stored food types for different algal classes.
- Incorrectly identifying the stage (gametophytic or sporophytic) where reduction division occurs.
- Misplacing the location of reduction division within the reproductive structures of plants.
- Difficulty in recalling the exact plant group associated with specific reproductive characteristics.
Revision tips
- Create a table summarizing the key features of Chlorophyceae, Phaeophyceae, and Rhodophyceae.
- Draw simplified life cycle diagrams for each plant group mentioned, highlighting where reduction division occurs.
- Focus on understanding the terms 'gametophyte' and 'sporophyte' and their roles.
- Practice identifying the specific reproductive organs (e.g., capsule, sporangia, anther, ovary) where meiosis happens.
Practice MCQs
Q1. Which of the following is NOT a basis for classifying algae into Chlorophyceae, Phaeophyceae, and Rhodophyceae?
Explanation: Algae are classified based on pigments, stored food, and cell wall composition, not primarily on habitat.
Q2. In which plant group does reduction division occur within the sporangia present on sporophylls?
Explanation: In ferns, the main plant body is sporophytic, and reduction division to form spores takes place in the sporangia located on sporophylls.
Q3. Floridean starch is the stored food in which class of algae?
Explanation: Floridean starch is characteristic of Rhodophyceae, commonly known as red algae.
Q4. Where does reduction division take place in the life cycle of a moss?
Explanation: In mosses, reduction division occurs within the capsule of the sporophyte to produce haploid spores.
Q5. Which pigments are primarily found in Phaeophyceae (brown algae)?
Explanation: Brown algae (Phaeophyceae) are characterized by the presence of chlorophylls a and c, along with the accessory pigment fucoxanthin.
Frequently asked questions
What are the main classes of algae according to NCERT?
According to NCERT, algae are primarily classified into three main classes: Chlorophyceae (green algae), Phaeophyceae (brown algae), and Rhodophyceae (red algae).
On what basis are algae classified?
Algae are classified based on their major photosynthetic pigments, the form of stored food, cell wall composition, and the number and position of flagella.
When does reduction division occur in a fern's life cycle?
In ferns, reduction division (meiosis) takes place within the sporangia, which are located on the sporophylls (leaves), to produce haploid spores.
What is the significance of reduction division in plant life cycles?
Reduction division (meiosis) is crucial as it produces haploid spores or gametes from diploid cells, which are essential for sexual reproduction and maintaining the characteristic chromosome number of a species across generations.
Where does meiosis happen in gymnosperms and angiosperms?
In gymnosperms, reduction division occurs in microsporangia (forming pollen) and megasporangia (forming megaspores). In angiosperms, it occurs in the anthers of the stamen (forming pollen) and the ovary of the pistil (forming eggs).
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